This invention relates to a tool coordinate system setting system and, more particularly, to a system for setting a tool coordinate system having a fixed relationship to a reference coordinate system of a robot.
The spread of robots has recently become quite conspicuous and robots are finding use in many fields. Under these circumstances, robots are required to perform both accurately and reliably.
Highly articulated robots have a large number of axes of motion and are extensively used for operations such as welding, due to their ability to execute sophisticated tasks. FIG. 5 is a perspective view of an industrial robot having five axes. In the Figure, BS denotes a base set on the floor of a factory or the like, the upper portion of the base being provided with a .theta.-axis drive mechanism 1 for driving a .theta. axis. Numeral 2 denotes a W-axis drive mechanism, 3 a W-axis arm driven by the W-axis drive mechanism 2, and 4 a U-axis arm driven by a U-axis drive mechanism 5 via a U-axis link 6. Numeral 7 denotes a robot wrist the distal end of which is provided with a hand 7a. Fixedly mounted on the hand 7a is a tool 8 such as a welding torch. Numeral 9 denotes an .alpha.-axis drive mechanism, and numeral 10 designates a .beta.-axis drive mechanism. The wrist 7, hand 7a and tool 8 are shown in enlarged form in FIG. 6.
As shown in FIG. 6, hand attitude vectors in the hand coordinate system are denoted , , , and the basic axes of the tool coordinate system are designated , , . Further, Oh represents the origin of the hand coordinate system, and TCP denotes the tool center point. Though the robot memorizes its own reference coordinate system as well as the hand coordinate system, difficulty is involved in setting the position of the tool 8 mounted on the hand 7a. Specifically, it is difficult for the robot to ascertain how the hand coordinate system and tool coordinate system are related to each other. In particular, since many kinds of tools 8 can be mounted on the hand 7a and are set at positions that differ from one another, ascertaining the correct position of a tool is a very difficult task.